Functions of anodizing in black anodized aluminium sheet

A black anodized aluminium sheet refers to an aluminium sheet going through the anodizing process during which its surface gets stronger and obtains the color of black. Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. In spite of its expensive cost, anodizing is applied frequently to meet further processing requirements of aluminium sheets and other metal sheets. The functions of a black anodized aluminium sheet is as below.

First, the abrasion resistance of the sheet gets improved. Ferrous metals are commonly anodized electrolytically in nitric acid or by treatment with red fuming nitric acid to form hard black Iron(II,III) oxide. This oxide remains conformal even when plated on wire and the wire is bent.

Second, corrosion resistance of a black anodized aluminium sheet is stronger than common sheets. The anodized layer functions to prevent galling of threaded components and to make dielectric films for electrolytic capacitors. When aluminum is used outdoors, a protective film is formed on the surface of the aluminum after the anode, which makes it difficult to oxidize and corrode, and can prolong life.

Third, a black anodized aluminium sheet gets insulated, widely used in electronics, such as hard disk housings, heat sinks, etc. After the anodization, the aluminum surface is not conductive, which is also a function of circuit protection.

Fourth, the oxide film on the surface can withstand a high temperature of 600 degrees Celsius. Anodic films are generally much stronger and more adherent than most types of paint and metal plating, but also more brittle. This makes them less likely to crack and peel from aging and wear, but more susceptible to cracking from thermal stress. However, 600 degrees are enough to resist most tough conditions in application.

Last, anodizing brings about color change, the appearance can be very beautiful. That’s how black gets onto the surface of an aluminium sheet. In addition, some aluminum products can oxidize a variety of colors, fonts, etc., to make a higher-grade gift box and the like!

In a word, Anodizing makes a black anodized aluminium sheet more resistant to abrasion, corrosion and temperature, and more adaptable to application needs.